Physical disability both gave me infinite time and made me realize that, when I had this same perspective, it was my cluttered mind and self expectations that were and still are the problem.
Do not be hard on yourself for the things you do not finish or when you lack the motivation to complete something. It is okay to do projects as a form of therapy and to walk away from them at any point that you are no longer getting value from them.
There was a Linux conference years ago where the speaker talked about her human byte, aka what one could process and hold in memory at one time. This memory is finite, and it is okay to acknowledge that. Some people excel at expanding their human byte through organizational skills, others may simply have an extraordinary size or persistence. We are not all equal. Mine is about average, if not a little small. I have something like an abstracted secondary space in my head for very loose note taking, but my actual persistence within any given main project focus is only around 3 weeks before my motivations drastically fade. Many times I learn whatever thing I was really interested in long before the project is complete and never finish it. I have learned to not let that bother me. I was an automotive painter early in life. That job is all about defeating self expectations for time spent because perfection is not subject to an individual's emotions or ego. So I have no doubts about what I am actually capable of doing if I really care. Like I said, there are many more reasons for exploring one's interests than simply finishing projects.
The psychology of this abstract space holds meaning far beyond first appearances. Do not hold back your self growth. That suppression is likely the underlying tension you are expressing. If you do not release this tension productively, you may regret the results that manifest as cognitive dissonance. The all or nothing premise is a fallacy that merits interpersonal exploration. In the past, I was blind to this as a fallacy. I'm not even sure if my explanation here would resonate with myself in the past, but hopefully it helps.